use std::fs::File;

struct A{
   a:i32,
}

fn f1(mut p:A){

   p.a = 10

}

fn f2(mut p:&mut A){

   p.a = 20

}


fn main() {
   let mut a = A{a:0};
   let mut b = &mut a;
   f2(b);
   f1(a);
   println!("{}",b.a);
}

